Rotary vane type positive displacement pump



P 1962 G. E. CARLSON 3,053,190

ROTARY VANE TYPE POSITIVE DISPLACEMENT PUMP Filed April' 10, 1961 FIG. FIG. 2.

INVENTOR GEORGE E. CARLSON United States Patent 3,053,199 ROTARY VANE TYPE POSITIVE DISPLAQEMENT PUMP George E. Carlson, Minneapolis, Minn, assignor to Minnesota Rubber Company, Minneapolis, Minn, a corporation of Minnesota Filed Apr. 11 1961, Ser. No. 102,057 4- Ciaims. ((11. 103117) This invention relates to impellers for rotary vane-type positive displacement pumps. More particularly, it relates to impellers for rotary Water pumps adapted for use in cooling systems of outboard motors.

One of the most serious problems in outboard motor maintenance is the early structural failure of the impeller in the water pump of the outboard motor which is utilized to cool the motor and consequent damage to the motor. The conventional impeller has a plurality of truly radially extending vanes which because of their design and the constant flexing to which they are subjected, function in an erratic manner as the impeller ages and the rubber from which the impeller is made fatigues. Often the impeller will fail completely within a very short period without any prior warning. Often the impeller will have a highly variable capacity or output which, of course, is also highly undesirable. My invention is directed toward overcoming these disadvantages.

It is a general object of my invention to provide a novel and improved impeller of simple and inexpensive construction and improved design.

A more specific object is to provide a novel and improved impeller simple and inexpensive to manufacture and designed so as to be capable of maintaining good capacity while formed of relatively soft, flexible, resilient material.

Another object is to provide a novel and improved impeller simple and inexpensive to manufacture and install and designed to provide a fairly constant capacity at a given r.p.m. under conditions where the back pressure is varied.

Another object is to provide a novel and improved impeller constructed and designed to minimize the adverse effects suffered from constant flexing of the vanes in a rotary vanetype positive displacement pump.

Another object is to provide a novel and improved impeller constructed and designed to provide its Water impelling functions over a longer useful life span.

Another object is to provide a novel and improved impeller constructed and designed to provide uniform flow regardless of direction in which it is driven and a more uniform flow than is normally provided by impellers of conventional construction.

These and other objects and advantages of my invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a side elevational view of my impeller.

FIG. 2 is a vertical sectional view of the same taken along line 22 of FIG. 1; and

FIG. 3 is an axial sectional view of a rotary vane-type positive displacement pump embodying my invention and showing the impeller in elevation.

One embodiment of my invention as shown in FIGS. 1-3, includes an outer casing 5 having opposite end walls 6 and 7 secured to the casing to form a pump chamber 8. A pump impeller shaft 9 is rotatably mounted and extends through the end walls 6 and 7 and may be provided with packing seals (not shown) to prevent leakage.

An impeller 1t? mounted on shaft 9 for rotation therewith includes a hub member 11 keyed to the shaft 9 and rotating therewith. Molded around the hub member 11 is a sleeve member 12 having a plurality of radially out- Wardly extending vanes 13 molded integrally therewith. Shaft 9 and impeller 10 are eccentric to the cylindrical wall 14 of pump chamber 8 to provide for the flexing of the vanes and the operation of the pump with rotation of shaft 9.

The chamber 8 is provided with an inlet port 15 and an outlet port 16, these ports being formed as best shown in FIG. 3 in the chamber walls and disposed oppositely with the outlet in communication with the spaces between the vanes when said spaces are decreasing in volume and with the inlet in communication with the spaces between the vanes when said spaces are increasing in volume.

Contact of the tips 17 of the vanes with the cylindrical wall 14 is maintained by the resiliency of the vanes 13 which are flexed with each revolution of the shaft 9. The sleeve member 12 and the vanes 13 are preferably formed of a flexible resilient material such as rubber so that the convex tips 17 will be constantly in registration with the inner walls of the chamber 8.

It will be noted that the vanes 13 increase in crosssectional dimensions from the tips 17 inwardly toward the roots 18 of the vanes. Each of the vanes 13 has a concavely shaped leading surface 1% and a convexly shaped trailing surface 20. Thus, each pair of adjacent vanes 13 define a concave pocket 21 therebetween which is generally cylindrical in shape.

It will be noted that each of the vanes 13 extends in its free form circumferentially of the sleeve member 12 and the hub .11 as well as the shaft 9 in a predetermined direction. I have found that by constructing the vanes 13 in this particular configuration and by rotating them in the direction in which their outermore portions extend, a much more efficient and desirable pumping action is attained. Thus when the impeller 10 is mounted upon the shaft 9 it is mounted so that the blades 13 extend in the direction in which the shaft 9 is to rotate during the normal operation of the outboard motor. It will be noted that the tips 17 of the vanes extend sufliciently circumferentially of the shaft 9 to define the cylindrically shaped pockets 21 and so that a line passing through the tip and the axis of rotation of the shaft 9 forms an angle of approximately 30 degrees with a second line passing through the axis of rotation of the shaft and the midpoint of a line drawn transversely through the roots 18 of the vanes. This can best be seen by reference to FIG. 1 wherein line 22 is drawn through the tip 17 and the axis of rotation of the hub member 11 and the line 23 is drawn through the axis of rotation of the hub member and through the midpoint of a line drawn transversely through the root 18 of the vane 13.

The hub member 11 is for-med of a rigid material such as plastic and is provided with axially extending walls 24 which are somewhat spaced from the more interior portions of the hub in order to more firmly secure the molded sleeve 12 to the hub member. Reference may be made to my co-pending application for US. Letters Patent Serial No. 91,974 filed by me February 27, 1961, and entitled Outboard Motor Impeller Hub, for further details on the construction of this hub member.

I have found that when an impeller of my design is extend in the direction of rotation of the shaft, a more mounted on the shaft 9 as shown, so that the vanes 13 efficient and longer lasting pump is provided. I have found that by constructing the impeller in accordance with my new design, the pump thereby provided will maintain excellent capacity or output even though the sleeve member 12 and the vanes 13 are manufactured from a relatively soft and flexible material. This is true because less damage results from the flexing to which the vanes are subjected since the flexing action is less severe upon the configuration of the vanes 13 when they are formed as shown in FIG. 1 as compared to the conventional radially extending vanes. Experience has shown that in the conventional type impeller where the vanes extend truly radial, the rubber from which the impeller is molded must necessarily be quite firm or the pump will fail at relatively low back pressures. My impeller has the advantage that relatively soft rubber material may be used for the molding of the impeller when the vanes 13 are formed as shown in FIG. 1 and the impeller is driven in the direction in which the vanes 13 extend circumferentially of the hub member. Since a more flexible material may be utilized, the damage inflicted upon the vanes by constant flexing is greatly diminished as compared to when a more firm or rigid material is utilized and hence the useful life span of one of my impellers is substantially greater than that of a conventional type impeller, for a material may be utilized in molding my new impeller which suffers less damage from repeated flexing.

My impeller has the advantage that it provides a fairly constant capacity at a given r.p.m. even though the back pressure varies. A standard or conventional type impeller will fluctuate substantially when the back pressure is varied. I have found that if two impellers are made of the same material and operated at the same r.p.m.s and the back pressures are varied, the impeller formed according to my design will perform in a more desirable manner than an impeller constructed according to the conventional design.

Since less damage results through an impeller of my design from the constant flexing to which the impeller is subjected, and since the action upon the configuration is less severe, an impeller constructed according to my invention has substantially longer useful life. In this connection it will be noted that the arcuate trailing surfaces 20 and the concave leading surfaces 19 are already arcuate in shape and hence the flexing to which they are subjected does less damage than would result from flexing of a straight surface such as is found upon the leading and trailing surfaces of an impeller of conventional design.

My impeller also has the advantage that the output capacity of the pump utilizing the impeller would not drop as rapidly, as the impeller ages or as the rubber fatigues, as is the case in the operation of conventional impellers. This is probably true because it is possible when molding an impeller of my design to utilize a softer rubber material since the firmness of the material is not as critical as when the blades extend truly radially. The fact that my vanes 13 extend in the direction of rotation tends to reduce the criticality of the softness of the rubber and hence permits the usage of a material which will withstand constant repeated flexing to a greater degree.

It should be noted that my impeller may be driven in reverse Without serious damage thereto and, moreover, will function in an improved manner when so driven, as compared to the conventional impeller, without serious flexing damage thereto. My impeller will pump at a constant capacity with as much as 30 p.s.i. of back pressure. I have found that my pump in. reverse can pump as much as 3.5 gallons per minute when there is no back pressure and that this capacity remains constant even though the impeller is being driven in a direction opposite to that in which the outermore portions of the vanes 13 extend.

From the above it can be seen that I have provided a novel and improved impeller of simple and inexpensive construction and highly improved design in that such an impeller is capable of maintaining good capacity while being formed of relatively soft resilient material with consequent greater or longer useful life. Thus my impeller not only functions in an improved manner but also provides this improved function over a longer period of time with consequent benefits to the manufacturer and user.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of my invention which consists of the matter shown and described herein and set forth in the appended claims.

What is claimed is:

l. A pump comprising a hollow casing having interior walls defining a generally cylindrical pump chamber, said pump chamber having an inlet and an outlet spaced circumferentially thereof, a shaft extending through said pump chamber parallel to the axis thereof and eccentrically disposed relative to said chamber, said shaft being rotatable about its longitudinal axis in a predetermined direction, a rigid tubular hub member fixedly mounted upon said rotary shaft in encircling relation for rotation therewith within said chamber, a sleeve member formed of rubber or the like molded onto said hub member in fixed encircling relation and extending coaxially thereof and being adapted to rotate therewith, and a plurality of flexible resilient vanes formed of rubber or the like and molded integrally with said sleeve member, said vanes extending radially outwardly from said sleeve member and engaging said walls of said pump chamber in flexed relation, said vanes in their free form being generally arcuate in shape and each extending outwardly from and circumferentially around said sleeve member in the direction of rotation of said shaft, each of said vanes having portions intermediate their outer ends and said sleeve member which have leading concavely shaped surfaces, said vanes being constructed in their free form to have a free leading tip having a portion extending at all times, while the pump is in operation, in the direction of rotation and concentric to the portion of the inner circumferential wall of said chamber which it engages and hav- :ing a leading edge and a base extending circumferentially of said sleeve member so that a line passing through said leading edge of the tip and the axis of rotation of said hub member extends at an angle approximating thirty degrees to a line passing through the axis of rotation of said hub and a point midway between the ends of the base of said vanes.

2. A pump comprising a hollow casing having interior walls defining a generally cylindrical pump chamber, said pump chamber having an inlet and an outlet spaced circumferentially thereof, a shaft extending through said pump chamber parallel to the axis thereof and eccentrically disposed relative to said chamber, said shaft being rotatable about its longitudinal axis in a predetermined direction, a rigid tubular hub member fixedly mounted upon said rotary shaft in encircling relation for rotation therewith, a sleeve member formed of rubber or the like molded onto said hub member in fixed encircling relation and extending coaxially thereof and being adapted to rotate therewith, and a plurality of flexible resilient vanes formed of rubber or the like and molded integrally with said sleeve member, said vanes extending radially outwardly from said sleeve member and engaging said walls of said pump chamber in flexed relation, said vanes in their free form being'generally arcuate in shape and each extending outwardly from and circumferentially around said sleeve member in the direction of rotation of said shaft, each of said vanes having a portion intermediate their outer ends and said sleeve member which has leading concavely shaped surfaces, the leading concavely shaped surfaces of each of said vanes in their free form terminating in a free leading tip element which at all times during rotation extends in the direction of rotation of said shaft without reversing itself and without flipping over, said tip element having a portion thereof at all times during rotation which engages and extends concentrically with the inner circumferential wall of said chamber.

3. A pump comprising a hollow casing having interior walls defining a generally cylindrical pump chamber, said pump chamber having an inlet and an outlet spaced circumferentially thereof, a shaft extending through said pump chamber parallel to the axis thereof and eccentrically disposed relative to said chamber, said shaft being rotatable about its longitudinal axis in a predetermined direction, a rigid tubular hub member fixedly mounted upon said rotary shaft in encircling relation for rotation therewith, a sleeve member formed of rubber or the like molded onto said hub member in fixed encircling relation and extending coaxially thereof and being adapted to rotate therewith, and a plurality of flexible resilent vanes formed of rubber or the like and molded integrally with said sleeve member, said vanes extending radially outwardly from said sleeve member and engagin said walls of said pump chamber in flexed relation, said vanes in their free form being generally arcuate in shape and each extending outwardly from and circumferentially around said sleeve member in the direction of rotation of said shaft, each of said vanes having a portion intermediate their outer ends and said sleeve member which has leading generally cylindn'cally shaped surfaces, the leading cylindrically shaped surfaces of each of said vanes in their free form terminating in a free leading tip element which at all times during the rotation of said shaft and hub member extends in the driection of rotation thereof and at all times has a portion thereof engaging and extending concentrically with the inner circumferential Wall of said chamber.

4. A pump comprising a hollow casing having interior walls defining a generally cylindrical pump chamber, said pump chamber having an inlet and an outlet spaced circumferentially thereof, a shaft extending through said pump chamber parallel to the axis thereof and eccentrically disposed relative to said chamber, said shaft being rotatable about its longitudinal axis in a predetermined direction, a rigid tubular hub member fixedly mounted upon said rotary shaft in encircling relation for rotation therewith within said chamber, a sleeve member formed of rubber or the like molded onto said hub member in fixed encircling relation and extending coaxially thereof and being adapted to rotate therewith, and a plurality of flexible resilient vanes formed of rubber or the like and molded integrally with said sleeve member and having free ends, said vanes extending radially outwardly from said sleeve member and engaging said walls of said pump chamber in flexed relation, said vanes in their free form being generally arcuate in shape and each extending outwardly from and circumferentially around said sleeve member in the direction of rotation of said shaft, each of said vanes having portions intermediate their outer ends and said sleeve member which have leading concavely shaped surfaces and trailing convexly shaped sur faces, each of said vanes extending at all times during the rotation of said shaft in the direction of its rotation without reversing any portion thereof and without any portion thereof flipping over, the trailing convexly shaped surface of each of said vanes terminating in a portion thereof which at all time during rotation thereof engages and extends concentrically with the inner circumferential wall of said chamber.

References (Iited in the file of this patent UNITED STATES PATENTS 2,070,738 Klein Feb. 16, 1937 2,605,715 Brant Aug. 5, 1952 2,659,313 Carson Nov. 17, 1953 2,699,188 McIntyre Feb. 16, 1954 2,712,792 Snyder July 12, 1955 2,789,511 Doble Apr. 23, 1957 FOREIGN PATENTS 730,806 Germany Ian. 18, 1943 1,213,695 France Nov. 2, 1959 

